Trees are an amazing
resource. Like other things that are wonderful gifts, we too
often take them for granted. It's understandable, I suppose,
because they're just there. They live and grow quietly, keeping to
themselves and putting on age and dignity while we're busy living our
own lives.
I had to clear an area for
a new garden recently and there was a white ash along the north edge
of the piece. It was borderline as far as interfering with the garden
was concerned but I took the tree anyway, mostly for selfish reasons.
It wasn’t especially sizable, only about 9 inches in diameter at
breast height. But as it turns out the darned thing was around 120
years old. That means it began its life only about 28 years after
Henry David Thoreau had died, just to give some perspective.
I reflected on that little
ash tree a bit after cutting it, much to the concern of my partner in
crime. A small section of the stump became something of a fixture on
the kitchen table. There was the small lamp I’d pulled up next to it,
and a sewing needle stuck into the bark. The needle is one I’d gotten
out of the medicine cabinet and the same one we use to extract
splinters from our hands, often splinters from trees older than this
ash. In this case the needle was for pointing to and keeping track of
the rings as I counted.
The selfish reason for
taking that ash tree was for heat. Ash has the unfortunate (for the
tree’s sake) distinction of being quick to season. So when the
fuelwood supply for winter starts looking lean, the ash trees in the
woodlot begin to get special attention. I like to think they can’t
feel me eyeing them that way but sometimes I wonder.
Some
Technicalities
It would probably be good
to get some basics out of the way, so here goes. Dendrology is
essentially the study of woody trees, shrubs and vines. And
dendrologists divide North American trees into two major groups.
Pines, spruces, cedars and the like (generally conifers or
cone-bearing trees) do not bear true flowers and they form one group.
The rest—often called broadleaved trees—are trees like oaks and
hickories that produce true flowers. The flowers aren’t necessarily
showy and conspicuous, as are those of the dogwood tree for example,
but they are nonetheless true flowers.
When it comes to technical
features in tree identification a fairly painless way to ease into it
is by observing a trait that is often pretty straightforward to see.
Broadleaved trees can have an alternate branching pattern with
alternate leaves, or an opposite branching pattern with opposite
leaves. It turns out that only a relative few have the opposite
pattern. The vast majority of broadleaved tree species are
alternate. So, by the process of elimination, if the tree in question
has the opposite pattern this narrows down the field enormously.
Trees growing in the open
may have branches, leaves and twigs close to the ground, but those
growing under the conditions of the forest tend to have relatively few
lower branches. This can make observation of leaf and twig details
difficult. Although it’s not quite as good as holding a specimen in
your hand, binoculars can definitely help. Otherwise we can rely
partly on what we might call circumstantial evidence.
For deciduous trees—trees
that drop their leaves in winter—there’s a reasonable degree of
certainty that many of the leaves on the ground under a given tree
came from that tree. Likewise, the fruits that litter the ground in
the fall or winter have a comparatively good chance of being from the
individual tree or trees above. Of course this is a bit more reliable
with heavy fruits like acorns and other nuts than with wind-dispersed
seeds like those in maple and ash.
Technical characteristics
aside, in some ways tree identification is like recognizing someone
you know in a crowd. If you were to try to describe what criteria you
use to conclude that the person you see is who you think it is, you
might have some difficulty. You just recognize that person without
thinking about the process. A similar thing begins to happen, with
practice, in tree identification. And the key, of course, is
practice.
Since it would be
impossible to cover the more than 800 species of trees native to North
America in an article like this, the objective will be to touch on
representatives occurring primarily in the northeastern US and leave
others for possible later articles.
Opposites
|
Fig. 1 White Ash treetops
Fig. 2 White Ash twig
Fig. 3 White Ash twigs with leaves and fruit
|
Ash
White ash
is one of several species of ash native to the northeast. All
the ashes have an opposite branching pattern. In other words, at
each point where a new twig grows from a bud on a small branch in the
spring, a nearly identical twig grows from a bud directly, or almost
directly, on the opposite side. This crosswise pattern in the
treetops can be evident even from the ground, and especially when
contrasted with neighboring tops of other trees that have an alternate
branching pattern. White ash has fairly stout twigs, a trait
that helps make this feature more discernible. Ash trees, as a
rule, have compound leaves. This means that each individual leaf
is divided into leaflets as shown in figure 3.
